Who are the most popular Bitcoin critics of our time?

Crypto critics:

https://amycastor.com/blog/

https://davidgerard.co.uk

https://schiffradio.com/

Warren Buffet

They are not necessarily predicting the collapse of bitcoin but they are against crypto for many reasons.

Something to think about - bitcoin only wins if it becomes a reserve currency. Until then it’s a negative sum game measured in dollars. Because it’s people swapping in and out dollars but with the expense of mining thrown in which has to be paid in dollars.

—-

People that are critical of bitcoin but pro crypto? … not sure that would be interesting.

At least this one has substance in his critique on anything 'Bitcoin' related: https://twitter.com/smdiehl

I would like to read some substantial critiques about Bitcoin. Are there any popular, smart thinkers who predict that Bitcoin will stay small or disappear completely?

You probably meant this, but I think "most thoughtful" (e.g. well-reasoned) is the better metric than most popular.